The Biostatistics Core will provide essential biostatistical support to Seattle Cancer Consortium Breast SPORE investigators. The Core links study design, data collection, measurements, and analysis to the critical hypotheses and questions studied by SPORE investigators whose research involves basic sciences, epidemiology, population studies, and clinical research. The Biostatistics Core will contribute to the SPORE mission through the following specific aims: 1. Study design: Define study hypotheses, study populations, and experimental measurements to answer research questions of interest, avoid systematic bias, and ensure a high likelihood of detection of biologically meaningful effects. 2. Analysis and interpretation: Identify and implement appropriate quantitative methods to address scientific questions of interest and provide valid statistical inferences about the evidence supporting the various study hypotheses. 3. Methodological development when needed: Modify existing approaches and develop novel study designs and methods to address problems arising from SPORE projects, where appropriate statistical methods are inadequate. SPORE biostatisticians have been closely involved with the projects in the SPORE. They will continue to collaborate as co-investigators on each project to ensure that studies are well designed and appropriately analyzed and interpreted. Moreover, the Core will provide consulting services to SPORE investigators for projects under the Research Developmental Program and the Career Development Program. The Core investigators have diverse and complementary expertise, and can conduct analyses using data from a wide variety of experimental technologies. For some of these technologies, analytic methods are still evolving. Core investigators are part of Consortium biostatistical research groups that are leaders in the areas of biomarker development, computational biology, and bioinformatics. In summary, the Core is well equipped to meet the diverse needs and address the translational aims of the Breast SPORE.